BODY AND MIND 3 in fact, if we like to look in the same way upon other subjects as we have been accustomed to look upon metaphysics—if we regard every man who has written about mathematics or mechanics as having just the same right to speak and to be heard that we give to every man who has written about metaphysics—then I think we shall find that exactly the same thing can be said about the most certain regions of human science. Those who like to read the last number of the Edinbttrgh Revzezv? for example, will find, from an article on " Comets and Meteors," that it is at present quite an open question whether bodies which are shot out from the sun by eruptive force may not come to circle about the sun in orbits which are like those of the planets. Now that is not an open question ; the supposition is an utterly absurd one, and has been utterly absurd from the time of Kepler. Again, those who are curious enough to read a number of pamphlets that are to be found here and there may think It is an open question whether the ratio of the circumference of a circle to its diameter may not be expressed by certain finite numbers. It is not an open question to Science ; it is only open to those people who do not know any Trigonometry, and who will not learn it In exactly the 1 October 1874.